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Title: STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS

Abstract

The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray binaries and radio millisecond pulsars. Comparing the numbers of these systems and interaction rates in different clusters drives our understanding of how cluster parameters affect the production of close binaries. In this paper we estimate stellar encounter rates ({Gamma}) for 124 Galactic globular clusters based on observational data as opposed to the methods previously employed, which assumed 'King-model' profiles for all clusters. By deprojecting cluster surface brightness profiles to estimate luminosity density profiles, we treat 'King-model' and 'core-collapsed' clusters in the same way. In addition, we use Monte Carlo simulations to investigate the effects of uncertainties in various observational parameters (distance, reddening, surface brightness) on {Gamma}, producing the first catalog of globular cluster stellar encounter rates with estimated errors. Comparing our results with published observations of likely products of stellar interactions (numbers of X-ray binaries, numbers of radio millisecond pulsars, and {gamma}-ray luminosity) we find both clear correlations and some differences with published results.

Authors:
; ; ;  [1]
  1. Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB, T5K 1V4 (Canada)
Publication Date:
OSTI Identifier:
22167491
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 766; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BINARY STARS; BRIGHTNESS; CATALOGS; COMPUTERIZED SIMULATION; DENSITY; DISTANCE; ERRORS; GALAXY CLUSTERS; INTERACTIONS; LUMINOSITY; MONTE CARLO METHOD; PROGENY; PULSARS; X RADIATION

Citation Formats

Bahramian, Arash, Heinke, Craig O., Sivakoff, Gregory R., and Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca. STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS. United States: N. p., 2013. Web. doi:10.1088/0004-637X/766/2/136.
Bahramian, Arash, Heinke, Craig O., Sivakoff, Gregory R., & Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca. STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS. United States. doi:10.1088/0004-637X/766/2/136.
Bahramian, Arash, Heinke, Craig O., Sivakoff, Gregory R., and Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca. 2013. "STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS". United States. doi:10.1088/0004-637X/766/2/136.
@article{osti_22167491,
title = {STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS},
author = {Bahramian, Arash and Heinke, Craig O. and Sivakoff, Gregory R. and Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca},
abstractNote = {The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray binaries and radio millisecond pulsars. Comparing the numbers of these systems and interaction rates in different clusters drives our understanding of how cluster parameters affect the production of close binaries. In this paper we estimate stellar encounter rates ({Gamma}) for 124 Galactic globular clusters based on observational data as opposed to the methods previously employed, which assumed 'King-model' profiles for all clusters. By deprojecting cluster surface brightness profiles to estimate luminosity density profiles, we treat 'King-model' and 'core-collapsed' clusters in the same way. In addition, we use Monte Carlo simulations to investigate the effects of uncertainties in various observational parameters (distance, reddening, surface brightness) on {Gamma}, producing the first catalog of globular cluster stellar encounter rates with estimated errors. Comparing our results with published observations of likely products of stellar interactions (numbers of X-ray binaries, numbers of radio millisecond pulsars, and {gamma}-ray luminosity) we find both clear correlations and some differences with published results.},
doi = {10.1088/0004-637X/766/2/136},
journal = {Astrophysical Journal},
number = 2,
volume = 766,
place = {United States},
year = 2013,
month = 4
}
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